In article
Guy King wrote:
The message
from Rob Morley contains these words:

Or just fore/aft, to keep the weight low. Probably not the safest thing
to have sticking out the side, though, and it might wreak havoc with the
aerodynamics.

Trailers don't do "aerodynamics".

I was thinking that they mostly sit in the wake of the car, and
extending the width might cause buffeting at the sides.